In-situ X-ray computed tomography during axial impregnation of unidirectional fiber beds is used to study coupled effects of fluid velocity, fiber movement and preferred flow channeling on permeability. In order to interpret the experimental measurements, a new computational tool for predicting axial permeability of very large 2D arrays of non-uniformly packed fibers is developed. The results show that, when the impregnation velocity is high, full saturation is attained behind the flow front and the fibers rearrange into a less uniform configuration with higher permeability. In contrast, when the velocity is low, fluid flows preferentially in the narrowest channels between fibers, yielding unsaturated permeabilities that are lower than those in the saturated state. These insights combined with a new computational tool will enable improved prediction of permeability, ultimately for use in optimization of composite manufacturing via liquid impregnation.

原位单向纤维床轴向浸渍过程中的X射线计算机断层摄影术用于研究流体速度，纤维运动和优选流动通道对渗透率的耦合作用。为了解释实验测量，开发了一种新的计算工具，用于预测非常大的二维阵列非均匀填充纤维的轴向渗透率。结果表明，当浸渍速度较高时，在流动前沿后方会达到完全饱和，纤维会重新排列成不太均匀的结构，具有较高的渗透性。相反，当速度较低时，流体优先在纤维之间的最窄通道中流动，从而产生的饱和渗透率低于饱和状态下的饱和渗透率。